Prior exercising equipment includes weights for lifting, stationary bicycles, rowing machines, and the like, all of which incorporate selected amounts of resistance against which one must apply his muscles to build up and strengthen them. In using such equipment, particularly in weight lifting, there is danger of injury to the muscles in attempting to lift too much weight, and this is especially true where rehabilitation of an injury is being attempted. Moreover, there is always danger of dropping the weights on parts of one's body such as the feet.
Another disadvantage in the use of such equipment is that, because the condition of the body varies from day to day, the amount of weight or resistance selected or set for one day may be excessive for another day, resulting in discouragement, frustration, and possibly bodily injury.
Exercising equipment such as stationary bicycles is very effective for strengthening the leg muscles, provided that the resistance is not set to an excessive amount, but one must then do something else, use another piece of equipment, to exercise the arms and other parts of the body.
Certain other pieces of exercising equipment utilize weights, overhead heavy metal plates and bars, rubber ropes, springs, benches and power-driven machines, all of which are apt to be dangerous and are so costly that they are usually available only in professional gymnasiums.
There are isometric exercises, in which parts of the body are applied against the resistance of an immovable object such as a wall or floor, or one set of muscles is applied statically against another set. In order for such exercises to become effective, a great deal of time, practice and patience is required.
Also, there are rope and pulley devices wherein ropes connect the hands and feet in an attempt to balance the arm muscles against the leg muscles, but such devices are adapted to be attached to a door knob while the body occupies strained and uncomfortable positions on the floor. Moreover, there is always a danger of injury due to the door knob breaking loose under the pulling and twisting forces exerted thereon.